With the growth of the use of personal communication devices, e.g., cell phones and two way radios, high performance and high frequency packaging materials have increased in importance. Desired characteristics for electronic packaging include high electric and thermal performance, thinness, low weight, small size, high component density, and low cost.
Conventional packages are fabricated from materials such as plastic, Teflon or ceramics. The type of material that is used depends on a number of factors which include frequency of operation, environment and cost. Plastic packages are typically the lowest in cost but may not be suitable for high frequencies of operation or very high temperatures. Applications that require exposure to extreme temperatures will commonly use ceramics. As the frequency of operation increases, it becomes advantageous to utilize materials that have lower dielectric constants to allow for the implementation so that the final package, with interconnects, will avoid noise or signal loss associated with high speed circuits.
Furthermore, as electronic devices continue to follow the trend of miniaturization, moisture and dust become more of a hindrance to maintaining functionality of such electronic devices. Patterned metal films generally have a thickness less than 25 μm and line widths of 50 μm or less for operating frequencies in the 1.0 to 100 GHz.
In U.S. Patent Application 2004/0207059, an adhesive between ceramic layer was used to seal a cavity. However, the adhesive material is substantially rigid, resulting in potential stress issues. Furthermore, the package is not inherently hermetic, the adhesive serves no purpose other than attaching the cover, and neither a multilayer interconnection nor low loss transmission lines are taught.
Accordingly, it is desirable to provide packaging having a hermetic cavity for microelectronic applications. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.